In recent years, there have been many studies of mirror drive devices using MEMS (Microelectronic Mechanical System) technology (also called micro-machine technology), which represent a fusion of an electronic circuit element with a mechanical element of minute size. As an example of a mirror drive system, Patent Reference 1 discloses an electromagnetic-type mirror drive device comprising a fixed frame, a movable frame, mirror, drive coil, and a pair of permanent magnets.
The movable frame is rotatably mounted with respect to the fixed frame, by means of a pair of torsion bars that extend on the same straight line. The mirror is arranged at the surface of the movable frame. The drive coil is wound in spiral fashion, seen from a direction orthogonal to the mirror surface, and is arranged on the movable frame. The pair of permanent magnets are arranged so that the drive coil is positioned therebetween, in a direction intersecting the direction of extension of the pair of torsion bars.
When current flows in the drive coil, a Lorentz force is generated in the drive coil by interaction with the magnetic field generated between the pair of permanent magnets, causing the movable frame to rotate with respect to the fixed frame. When the movable frame rotates, the direction of the mirror that is arranged at the surface of the movable portion is altered, resulting in an alteration in the optical path of the reflected light from the mirror. Such a mirror drive device is applied for example to optical switches for optical communication and/or optical scanners.